Building structure

Abstract

This reduces the building's response acceleration while suppressing the deformation of the seismic isolation layer during an earthquake. [Solution] The seismic isolation structure comprises a first building section 100 constructed on a first seismic isolation layer 31, which is configured with a first seismic isolation bearing 110 and a first damping device 120 installed on a foundation section 50, and a second building section 200 constructed at a distance from the first building section 100 on a second seismic isolation layer 32, which is configured with a second seismic isolation bearing 210 and a second damping device 220 installed on a foundation section 50. The first seismic isolation bearing 110 has a restoring force, the second seismic isolation bearing 210 has a restoring force of approximately 0, the upper end of the second building section 200 is rigidly connected to the sixth layer 26 above the position K which is the node of the secondary mode of the natural vibration mode in the first building section 100, and at least one of the horizontal stiffness of the second building section 200 and the damping performance of the second damping device 220 is adjusted so that the amount of horizontal deformation of the second seismic isolation layer 32 in the secondary mode is 0 or approximately 0.

Description

[Technical Field]

[0001] The present invention relates to a building structure. [Background Art]

[0002] Patent Document 1 discloses a technology related to a base-isolated structure. In this prior art, the base-isolated structure includes a core portion and a main building portion adjacent to the core portion, and is a multi-layer base isolation structure having a foundation base isolation layer provided below the core portion and the main building portion, and an intermediate base isolation layer provided at an intermediate portion of the main building portion; the core portion above the intermediate base isolation layer and an upper frame above the intermediate base isolation layer in the main building portion are integrally formed; the core portion below the intermediate base isolation layer and a base frame below the intermediate base isolation layer in the main building portion are each configured independently; and a wall portion of the core portion above the intermediate base isolation layer is configured with lower rigidity than a wall portion of the core portion below the intermediate base isolation layer.

[0003] Patent Document 2 discloses a technology related to a building structure. In this prior art, the building structure includes a main frame portion of a base-isolated structure in which a first damping device is provided on a base isolation layer, and a core portion of a base-isolated structure that is constructed at an interval from the main frame portion, joined to a node of a higher-order mode of the natural vibration mode of the main frame portion, and provided with a second damping device on a base isolation layer; and the core portion has rigidity such that deformation of the second base isolation layer of the core portion in the higher-order mode becomes zero or substantially zero. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2020-012254 [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2022-158561 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] If the rigidity of the seismic isolation layer is reduced to enhance the seismic isolation effect of a seismic isolation structure, the deformation of the seismic isolation layer will increase, potentially leading to collisions with retaining walls, for example. However, if the damping device is increased to suppress the deformation of the seismic isolation layer, the deformation of the seismic isolation layer will decrease, but the response acceleration of the superstructure will increase, reducing the seismic isolation effect.

[0006] Furthermore, the main reason for the increase in the response acceleration of this superstructure is thought to be the increase in higher-order modes of the building due to the increased damping of the damping device.

[0007] Thus, it can be said that there is a trade-off between suppressing the deformation of the seismic isolation layer during an earthquake and reducing the response acceleration of the building.

[0008] In view of the above facts, the present invention aims to reduce the response acceleration of a building while suppressing the deformation of the seismic isolation layer during an earthquake. [Means for solving the problem]

[0009] The first embodiment is a building structure comprising: a first building section of a seismic isolation structure constructed on a first seismic isolation layer configured by installing a first seismic isolation bearing and a first damping device on a substructure; and a second building section of a seismic isolation structure constructed at a distance from the first building section on a second seismic isolation layer configured by installing a second seismic isolation bearing and a second damping device on the substructure, wherein the first seismic isolation bearing has a restoring force, the second seismic isolation bearing has a restoring force of approximately 0, the upper end of the second building section is rigidly connected to a layer above the position that is a node of a higher-order mode of the natural vibration mode in the first building section, and the damping performance of the second damping device is adjusted so that the amount of horizontal deformation of the second seismic isolation layer in the higher-order mode is 0 or approximately 0.

[0010] In the building structure of the first embodiment, the upper end of the second building section is rigidly connected to a layer above the position that corresponds to the node of the higher-order mode of the natural vibration mode in the first building section, and the damping performance of the second damping device is adjusted so that the amount of horizontal deformation of the second seismic isolation layer in the higher-order mode is 0 or approximately 0.

[0011] Thus, for higher-order mode shaking during an earthquake, the horizontal deformation of the second seismic isolation layer is 0 or nearly 0, so the deformation or velocity input to the second damping device is 0 or nearly 0. Therefore, for higher-order mode shaking during an earthquake, the damping force exerted by the second damping device is 0 or nearly 0, and the response acceleration in higher-order modes due to the damping force of the second damping device is reduced.

[0012] On the other hand, in response to the primary mode of shaking during an earthquake, the second damping device works together with the first damping device to exert damping force, suppressing the deformation of the first and second seismic isolation layers.

[0013] Therefore, it is possible to reduce the response acceleration of the first building section while suppressing excessive deformation of the first and second seismic isolation layers during earthquakes, especially mega-earthquakes.

[0014] Furthermore, this method can be applied to buildings where the location of the node for the higher-order modes of the natural vibration modes in the first building section does not coincide with the floor.

[0015] Furthermore, compared to the case where the upper end of the second building section is rigidly connected to a position that corresponds to a node of a higher-order mode of the natural vibration mode in the first building section, the increase in the horizontal stiffness of the second building section can be suppressed.

[0016] The second embodiment is a building structure according to the first embodiment, wherein the horizontal rigidity of the second building section is adjusted in addition to the damping performance of the second damping device so that the amount of horizontal deformation of the second seismic isolation layer in the higher-order mode is 0 or approximately 0.

[0017] In the building structure of the second embodiment, the damping performance of the second damping device and the horizontal stiffness of the second building section are both adjusted so that the horizontal deformation of the second seismic isolation layer in higher modes is 0 or approximately 0. Therefore, the damping performance of the second damping device can be reduced compared to the case where adjustment is made using only the damping performance of the second damping device.

[0018] The third embodiment is the building structure described in the second embodiment, wherein the damping performance of the second damping device is higher than that of the first damping device.

[0019] In the building structure according to the third aspect, the damping performance of the second damping device is higher than that of the first damping device, so the horizontal rigidity of the second building portion can be made smaller than in a case where the damping performance of the second damping device is lower than that of the first damping device. Effects of the Invention

[0020] According to the present invention, the response acceleration of a building can be reduced while suppressing deformation of a seismic isolation layer during an earthquake. Brief Description of the Drawings

[0021] [Figure 1] FIG. 1 is an elevation view schematically showing the structure of a base-isolated building according to an embodiment. [Figure 2] FIG. 2 is a model diagram of a numerical analysis model of the base-isolated building of FIG. 1. [Figure 3] FIG. 3 is a graph showing mode displacements (real parts) obtained by complex eigenvalue analysis of a base-isolated building in which deformation of a second seismic isolation layer is adjusted to 0 or substantially 0. [Figure 4] FIG. 4 is a graph showing mode displacements (real parts) obtained by complex eigenvalue analysis of a base-isolated building in which deformation of a second seismic isolation layer is adjusted to 0 or substantially 0. [Figure 5] FIG. 5 is a graph of complex eigenvalue analysis showing mode displacements of each layer when the reinforcement coefficient α is 1 time. [Figure 6] FIG. 6 is a graph of complex eigenvalue analysis showing mode displacements of each layer when the reinforcement coefficient α is 5 times. [Figure 7] FIG. 7 is a graph showing the relationship between the response magnification at the top of a base-isolated building in which deformation of a second seismic isolation layer is adjusted to 0 or substantially 0, and the natural frequency. [Figure 8] FIG. 8 is a graph of time history response analysis showing the maximum relative displacement of each layer. [Figure 9] FIG. 9 is a graph of time history response analysis showing the maximum acceleration response of each layer. [Figure 10] FIG. 10 is a graph of time history response analysis showing the maximum interlayer deformation angle of each layer. [Figure 11]This graph shows the mode displacement (real part) obtained by complex eigenvalue analysis when the second damping device is adjusted so that the deformation of the second seismic isolation layer is 0 or approximately 0, starting from the state in Figure 5 where the reinforcement coefficient α is 1. [Figure 12] This is a model diagram of a numerical analysis model for another example of a seismically isolated building. [Figure 13] This is a model diagram of a numerical analysis model for another example of a seismically isolated building. [Figure 14] This is a model diagram of the numerical analysis model for the seismically isolated building in the comparative example. [Figure 15] Figure 14 is a graph of complex eigenvalue analysis showing the relationship between the damping coefficient and the mode displacement of each floor of the comparative example seismically isolated building. [Modes for carrying out the invention]

[0022] <Embodiment> The building structure of one embodiment of the present invention will be described.

[0023] The two orthogonal horizontal directions are designated as the X and Y directions, and are indicated by arrows X and Y, respectively. The vertical direction perpendicular to the X and Y directions is designated as the Z direction, and is indicated by arrow Z.

[0024] Each drawing is only a schematic representation. The dimensions and proportions of the elements shown in the drawings may not necessarily match those of reality. Even between multiple drawings, the dimensions, proportions, and number of elements may not necessarily match. Hatching to represent cross-sections is omitted if it makes the drawing difficult to read.

[0025] Furthermore, explanations of configurations not directly related to the present invention and well-known configurations may be omitted or simplified.

[0026] [Building structure] First, the structure of a base-isolated building to which the building structure of this embodiment is applied will be described. Note that the base-isolated building is not limited to any of the following: reinforced concrete, steel frame, steel-reinforced concrete, wood, or hybrid structures thereof.

[0027] As shown in Figure 1, the building structure 10 of this embodiment includes a foundation 50 as an example of a substructure, a first building section 100 constructed on a first seismic isolation layer 31, and a second building section 200 constructed on a second seismic isolation layer 32. The first seismic isolation layer 31 is configured to have a first seismic isolation bearing 110 and a first damping device 120 provided on the foundation 50. The second seismic isolation layer 32 is configured to have a second seismic isolation bearing 210 and a second damping device 220 provided on the foundation 50.

[0028] The base-isolated building 12 to which this building structure 10 is applied is a base-isolated building, and has a reinforced concrete foundation 50 and a steel-framed building section 20 as an example of a superstructure. The foundation 50 is provided in the ground G and has a base plate 52 and a retaining wall 54 rising from the outer perimeter of the base plate 52, forming a base isolation pit.

[0029] The building section 20 is composed of a first building section 100 and a second building section 200. In this embodiment, the building section 20 is a nine-story, eight-floor steel-framed building with a rigid frame structure, but it is not limited to this.

[0030] The building section 20 of this embodiment has a nine-story structure and is an eight-story rigid frame structure, so from the bottom up, the floors are numbered 1st floor 21, 2nd floor 22, 3rd floor 23, 4th floor 24, 5th floor 25, 6th floor 26, 7th floor 27, 8th floor 28, and 9th floor 29. Also, the first floor is numbered 1F, the second floor 2F, the third floor 3F, the fourth floor 4F, the fifth floor 5F, the sixth floor 6F, the seventh floor 7F, and the eighth floor 8F.

[0031] The first building section 100 is composed of an upper building section 102 and lower building sections 104A and 104B. The lower building sections 104A and 104B extend downward from both sides of the upper building section 102. The second building section 200 is positioned at a distance between the lower building sections 104A and 104B. The upper end of the second building section 200 is rigidly connected to the lower end of the upper building section 102 of the first building section 100.

[0032] In this embodiment, the upper building section 102 of the first building section 100 constitutes the 6th to 8th floors, and the lower building sections 104A, 104B and the second building section 200 constitute the 1st to 5th floors. Furthermore, when it is necessary to distinguish and describe each layer and floor of the second building section 200 and the lower building sections 104A and 104B, it should be described as "the fifth layer 25 of the second building section 200" or "the first floor 1F of the lower building section 104A," etc. Also, when describing the lower building section 104A and the lower building section 104B without distinguishing between them, the A and B after the reference numerals should be omitted and it should be referred to as the lower building section 104.

[0033] In this embodiment, the second building section 200 constitutes a part of the center core of the building section 20, and in this embodiment, it constitutes the first floor (1F) to the fifth floor (5F). The "core" is the central part of the structural framework, which is made up of load-bearing walls that resist earthquakes and the like, and houses facilities such as stairs, toilets, pipe shafts, and elevators. As mentioned above, the second building section 200 constitutes the first floor (1F) to the fifth floor (5F) of the center core, and the center core is also continuously provided within the upper building section 102 of the first building section 100.

[0034] In this embodiment, the sixth layer 26 of the building section 20 is the lowest layer of the upper building section 102 and also the highest layer of the lower building sections 104A, 104B and the second building section 200. In other words, the sixth layer 26, which is the highest layer and upper end of the second building section 200, and the sixth layer 26, which is the lowest layer and lower end of the upper building section 102 of the first building section 100, are integrated into a single structure. Furthermore, this structure is configured such that the upper end of the second building section 200 is rigidly connected to the lower end of the upper building section 102 of the first building section 100.

[0035] In the first building section 100, the position K that corresponds to the node of the higher-order natural vibration mode, the second-order mode in this embodiment, is located between the fifth floor 25 and the sixth floor 26. From another perspective, the position K that corresponds to the node of the second-order mode is located on the fifth floor (5F). In this embodiment, the sixth floor 26 of the first building section 100, which is the floor directly above the position K of this node, is rigidly connected to the sixth floor 26 of the second building section 200, which is the upper end of the second floor 26. Here, the term "higher-order mode" in this specification refers to the second-order mode or higher, and in this embodiment, as mentioned above, the second-order mode will be used as an example for explanation.

[0036] As mentioned above, the second building section 200 is constructed with a gap between it and the lower building sections 104A and 104B, and this is also illustrated in Figure 1. However, in reality, the lower building sections 104A and 104B of the first building section 100 and the second building section 200 are connected by expansion joints, etc. In other words, "the second building section 200 is constructed with a gap between it and the lower building sections 104A and 104B" refers to a structure that is structurally separated from the lower building sections 104A and 104B.

[0037] The base slab 52 of the foundation 50 is equipped with a first seismic isolation bearing 110 and a first damping device 120, and a second seismic isolation bearing 210 and a second damping device 220. The first seismic isolation bearing 110 and the first damping device 120 are installed directly beneath the lower building section 104 of the first building section 100. The second seismic isolation bearing 210 and the second damping device 220 are installed directly beneath the second building section 200. In addition, piles may be provided directly beneath the first seismic isolation bearing 110 and the second seismic isolation bearing 210 of the base slab 52 of the foundation 50 in the ground G.

[0038] The first seismic isolation bearing 110 supports the lower building section 104 of the first building section 100, and the second seismic isolation bearing 210 supports the second building section 200. The first damping device 120 is connected to the base slab 52 of the foundation section 50 and the first layer 21 of the first building section 100, and the second damping device 220 is connected to the base slab 52 of the foundation section 50 and the first layer 21 of the second building section 200.

[0039] The first seismic isolation bearing 110 is a bearing that possesses a restoring force that combines isolation function and damping function due to energy absorption performance. Specifically, examples include laminated rubber bearings, laminated rubber bearings with lead plugs, high-damping rubber bearings, and spherical sliding bearings. The second seismic isolation bearing 210 is a bearing that has an isolation function and a restoring force that is extremely small, almost zero. Note that "almost zero" is a range that can be practically ignored, and it is a level at which it can be considered "zero" in structural design. Specifically, examples include sliding bearings and rolling bearings. Furthermore, "restoring force" is the force that tries to return the building section 20 to the center when the building section 20 is displaced horizontally relative to the center of vibration.

[0040] From another perspective, the first seismic isolation bearing 110 has horizontal rigidity, while the second seismic isolation bearing 210 has approximately zero horizontal rigidity. "Approximately zero" means that it is practically negligible and can be considered "zero" in structural design.

[0041] The first damping device 120 and the second damping device 220 are devices that have a damping function based on energy absorption performance, and in this embodiment, they are devices that have the function of damping the horizontal relative displacement between the foundation 50 and the building 20.

[0042] The base slab 52 of the foundation 50, the building section 20, and the first floor 21 form a seismic isolation layer 30. The portion of the seismic isolation layer 30 where the first seismic isolation bearing 110 and the first damping device 120 are installed directly below the lower building section 104 of the first building section 100 is designated as the first seismic isolation layer 31, and the portion where the second seismic isolation bearing 210 and the second damping device 220 are installed directly below the second building section 200 is designated as the second seismic isolation layer 32.

[0043] The damping performance of the second damping device 220 and the horizontal stiffness of the second building section 200 are adjusted so that the amount of horizontal deformation of the second seismic isolation layer 32 in the second mode of the first building section 100 of the building section 20 of the seismically isolated building 12 is 0 or approximately 0 in this embodiment.

[0044] Furthermore, "damping performance" refers to the damping coefficient in the case of velocity-dependent damping devices such as oil dampers and viscous dampers, and is determined from the area traced by the history up to a predetermined deformation in the case of displacement-dependent damping devices such as hysteresis dampers.

[0045] Furthermore, the horizontal rigidity of the second building section 200 can be adjusted by adjusting the load-bearing capacity of structural members such as columns, beams, slabs, and shear walls that constitute the second building section 200, or by adjusting the performance and number of reinforcing members such as braces.

[0046] Furthermore, the horizontal deformation amount of the second seismic isolation layer 32 in the secondary mode of the first building section 100 of the seismically isolated building 12 is 0 or approximately 0, which means that the horizontal displacement amount of the foundation section 50 of the first floor 21 of the second building section 200 relative to the base slab 52 in the secondary mode of the first building section 100 is 0 or approximately 0.

[0047] "Approximately 0" refers to a range where the horizontal displacement of the first floor 21 of the second building section 200 relative to the base 52 is substantially negligible compared to the design deformation of the entire building, and is therefore negligible in terms of structural design.

[0048] Figure 2 is a model diagram of the analysis model of the base-isolated building 12 shown in Figure 1. In Figure 2, the squares at the bottom represent the first floor 21, and the circles above them represent the second floor 22 to the ninth floor 29.

[0049] Figure 3 is a graph plotting the relative horizontal displacement of each layer as a result of complex eigenvalue analysis of the analytical model in Figure 2. [100-1] is the graph of the first mode of the first building section 100, [100-2] is the graph of the second mode of the first building section 100, [100-3] is the graph of the third mode of the first building section 100, and [200-2] is the graph of the second mode of the second building section 200. This convention is also followed hereafter.

[0050] Figure 4 shows the graphs of the secondary modes of the first building section 100 and the second building section 200 in Figure 3. Note that in Figure 3, the "secondary modes of the second building section 200" refer to the secondary modes of the natural vibration modes of the first building section 100. This distinction will continue throughout the text.

[0051] Then, the damping performance of the second damping device 220 and the horizontal stiffness of the second building section 200 are adjusted so that the displacement of the first floor 21 (see Figure 1) of the second building section 200 is 0 or approximately 0 (see section S in the figure). In the graphs of Figures 3 and 4, the displacement of the first floor 21 (see Figure 1) in the secondary mode of the first building section 100 is adjusted to 0. Details of the graphs in Figures 3 and 4 will be described later.

[0052] Here, there is no established analytical method or design method for adjusting the damping performance of the second damping device 220 and the horizontal stiffness of the second building section 200 so that the horizontal deformation of the second seismic isolation layer 32 in the second mode of the first building section 100 of the seismically isolated building 12 is 0 or approximately 0. Therefore, at present, we are changing the parameters and performing complex eigenvalue analysis to find combinations in which the horizontal deformation of the second seismic isolation layer 32 is 0 or approximately 0.

[0053] [Effect] Next, the operation of this embodiment will be described.

[0054] In the base-isolated building 12 to which the building structure 10 of this embodiment is applied, the sixth story 26, which is the upper end of the second building section 200 of the building section 20, is rigidly connected to the fifth story 25, which is directly above the position K that is the node of the second mode of the natural vibration mode in the first building section 100, thereby integrating them, and the damping performance of the second damping device 220 and the horizontal rigidity of the second building section 200 are adjusted.

[0055] Thus, for the secondary mode shaking during an earthquake, the horizontal deformation of the second seismic isolation layer 32 is 0 or nearly 0, so the deformation or velocity input to the second damping device 220 is 0 or nearly 0. Therefore, for the secondary mode shaking during an earthquake, the damping force exerted by the second damping device 220 is 0 or nearly 0, and the response acceleration in the secondary mode due to the damping force of the second damping device 220 is reduced.

[0056] On the other hand, in response to the primary mode shaking during an earthquake, the second damping device 220 exerts damping force together with the first damping device 120, suppressing the deformation of the first seismic isolation layer 31 and the second seismic isolation layer 32.

[0057] Therefore, it is possible to reduce the response acceleration of the first building section 100 while suppressing excessive deformation of the first seismic isolation layer 31 and the second seismic isolation layer 32, i.e., the seismic isolation layer 30, during earthquakes, especially mega-earthquakes. Furthermore, since excessive deformation of the first seismic isolation layer 31 and the second seismic isolation layer 32 during mega-earthquakes is suppressed, the risk of the building section 20 colliding with the retaining wall 54 of the foundation section 50 is reduced.

[0058] Furthermore, this method can also be applied to buildings where the location K, which is a node of the second mode of the natural vibration mode in the first building section 100, does not coincide with the floor.

[0059] Furthermore, compared to the case where the upper end of the second building section 200 is rigidly connected to a position K that is a node of the second mode of the natural vibration mode in the first building section 100, the increase in the horizontal stiffness of the second building section 200 can be suppressed.

[0060] Here, if the upper end of the second building section 200 is rigidly connected to position K, which is a node of the second mode of the natural vibration mode in the first building section 100, then when the second building section 200 deforms, the deformation of the second seismic isolation layer 32 will not be zero or nearly zero. Therefore, it is necessary to increase the horizontal stiffness of the second building section 200, for example, by increasing the reinforcement coefficient α, which will be described later, to about five times.

[0061] In contrast, if the upper end of the second building section 200 is rigidly connected to a layer above the position K which is the node of the second mode of the natural vibration mode in the first building section 100, the deformation of the second building section 200 can be adjusted so that the deformation of the second seismic isolation layer 32 becomes 0 or approximately 0. Therefore, even if the horizontal stiffness of the second building section 200 is doubled or equal to the reinforcement coefficient α described later, it is possible to adjust the deformation of the second seismic isolation layer 32 to be 0 or approximately 0.

[0062] Furthermore, the damping performance of the second damping device 220 is higher than that of the first damping device 120. Therefore, the horizontal rigidity of the second building section 200 can be reduced.

[0063] [Numerical Analysis]

[0064] Next, we will explain, using numerical analysis, that a base-isolated building 12 to which the building structure 10 of this embodiment is applied can reduce the building's response acceleration while suppressing the deformation of the base isolation layer during an earthquake.

[0065] (Comparative example) First, let's explain the seismically isolated building used as an example.

[0066] The building section 902 of the base isolation building 900 of the comparative example base isolation structure shown in Figure 14 is a configuration in which the second building section 200 of the base isolation building 12 of this embodiment (see Figures 1 and 2) is integrated with the first building section 100, and is a model diagram of the analysis model corresponding to Figure 2. Similarly, the squares at the bottom represent the first floor, and the circles above them represent the second to ninth floors. Reference numeral 930 denotes the base isolation layer, reference numeral 910 denotes the base isolation bearing, and reference numeral 920 denotes the damping device.

[0067] Furthermore, the mass of the lower building section 904 of the building section 902 of the comparative example, specifically the section below the sixth floor, was set to be equal to the sum of the mass of the lower building section 104 of the first building section 100 and the mass of the second building section 200 of the seismically isolated building 12 (see Figure 2) of this embodiment.

[0068] (Relationship between deformation of the seismic isolation layer and response acceleration in the comparative example of a seismically isolated building) Next, we will explain that in the comparative example seismic isolation building 900 shown in Figure 14, there is a trade-off relationship between suppressing the deformation of the seismic isolation layer 930 during an earthquake and reducing the response acceleration of the building section 902.

[0069] The graph in Figure 15 shows the relationship between the response magnification at the top of the building section 902 and the natural frequency in the comparative example seismically isolated building 900, obtained by complex eigenvalue analysis while varying the damping performance of the damping device 920 in the seismic isolation layer 930. The response magnification is the value obtained by dividing the top acceleration by the ground acceleration. The damping performance of the damping device 920 is the damping rate h.

[0070] As can be seen from the graph in Figure 15, in the primary mode, the larger the damping rate h of the damping device 920 and the higher the damping performance, the lower the response magnification at the top of the building section 902 in the comparative example seismic isolation building 900 (see FA in the graph). However, in the secondary and tertiary modes, the larger the damping rate h of the damping device 920 and the higher the damping performance, the higher the response magnification. In other words, there is a trade-off relationship between the deformation of the seismic isolation layer 930 and the acceleration response of the building section 902.

[0071] (Relationship between deformation of the seismic isolation layer and response acceleration in the seismically isolated building of this embodiment) Next, we will explain that in the seismically isolated building 12 of this embodiment shown in Figures 1 and 2, it is possible to suppress the deformation of the seismic isolation layer 30 during an earthquake while suppressing the response magnification of the building section 20 in higher-order modes.

[0072] First, let's explain the analysis conditions. The stiffness (km) of the first seismic isolation layer 31 of the first building section 100 was set so that the seismic isolation period of the entire building section 20 is 4 seconds. Note that "seismic isolation period of the entire building section 20" refers to the period calculated from the mass of the building section 20 and the stiffness of the entire seismic isolation layer 30, when the building section 20, composed of the first building section 100 and the second building section 200, is treated as a single rigid body.

[0073] The stiffness (ks) of the second seismic isolation layer 32 of the second building section 200 was set to 0. The damping of the building section 20 was set so that the damping rate h was 2% of the period when the building section 20 was assumed to be a non-seismic isolation structure (a configuration without a seismic isolation layer 30) built on the foundation section 50.

[0074] The damping of the seismic isolation layer 30 was set to a damping rate h of 40% for a seismic isolation period of 4 seconds, and the damping of the first seismic isolation layer 31 and the damping of the second seismic isolation layer 32 were set to a ratio of 1:4. The horizontal stiffness and mass of the lower building section 104 of the first building section 100 were set to 2 / 3 times that of the lower building section 904 of the building section 902 of the comparative example seismic isolation building 900 (see Figure 14), and the horizontal stiffness and mass of the second building section 200 were set to 1 / 3 times.

[0075] The horizontal stiffness of the second building section 200 was analyzed by multiplying the reinforcement coefficient α by 1.0, 2.0, 3.0, 4.0, and 5.0, respectively. The reinforcement coefficient is a multiplier for the horizontal stiffness of the lower building section 904 (see Figure 14) of the building section 902 of the comparative example base-isolated building 900. Therefore, for example, if the reinforcement coefficient α is 2, the standard stiffness of the second building section 200 is 1 / 3 that of the lower building section 904 of the comparative example, so multiplying this by 2 gives 2 / 3 that of the lower building section 904 of the comparative example. In other words, the horizontal stiffness of the second building section 200 with a reinforcement coefficient α of 2 and the horizontal stiffness of the lower building section 104 of the first building section 100 are both 2 / 3 that of the lower building section 904, and are therefore the same.

[0076] As mentioned above, the rigidity of the second building section 200 can be reinforced (adjusted) by adjusting the load-bearing capacity of structural members such as columns, beams, slabs, and shear walls that constitute the second building section 200, as well as the performance and number of reinforcing members such as braces.

[0077] Furthermore, Figures 3 and 4, mentioned above, are graphs of the results of complex eigenvalue analysis when the reinforcement coefficient α is doubled, and under these conditions, the horizontal deformation of the second seismic isolation layer 32 in the secondary mode becomes 0 or approximately 0.

[0078] Figure 5 shows the graph when the reinforcement coefficient α is 1, and Figure 6 shows the graph when the reinforcement coefficient α is 5. From these graphs, it can be seen that when the reinforcement coefficient α is 1 and 5, the deformation of the second seismic isolation layer 32 is large and not 0 or nearly 0.

[0079] Figure 7 is a graph showing the relationship between the response magnification at the top and the natural frequency for the base-isolated building 12 of this embodiment and the base-isolated building 900 of Figure 14, both adjusted so that the horizontal deformation of the second isolation layer 32 in the secondary mode of Figure 4 is 0 or nearly 0. From the graph in Figure 7, the response magnification in the primary mode is approximately the same for the base-isolated building 12 of this embodiment and the base-isolated building 900 of the comparative example (see FA in the graph). However, the response magnifications in the secondary and tertiary modes are lower for the base-isolated building 12 of this embodiment than for the base-isolated building 900 of the comparative example (see FB in the graph).

[0080] Therefore, it can be seen that a base-isolated building 12 to which the building structure 10 of this embodiment is applied reduces the building's response acceleration while suppressing the deformation of the base isolation layer during an earthquake.

[0081] (Time history response analysis) Next, we will show an example of the effects obtained from time history response analysis.

[0082] The analysis conditions are the same as those for the complex eigenvalue analysis described above. The reinforcement coefficient α is 2.0. The seismic isolation period was set to 4 seconds. The damping performance of the first damping device 120 and the second damping device 220 of the seismically isolated building 12 in this embodiment (see Figures 1 and 2) and the damping device 920 of the comparative example seismically isolated building 900 (see Figure 14) was set based on the specifications of actual oil dampers, and the damping force by the oil dampers was modeled as bilinear. In this case, the number of dampers was adjusted so that the damping coefficient h was 40% for a deformation of 500 mm in the seismically isolated layer 930 of this embodiment. The input ground motion is the JMA KOBE (Japan Meteorological Agency) observation wave from the Great Hanshin Earthquake. The inter-story drift angle was calculated assuming a uniform floor height of 4 m.

[0083] Figures 8 to 10 show graphs of the time history response analysis results. Figure 8 is a graph showing the maximum relative displacement of each layer, Figure 9 is a graph showing the maximum acceleration response of each layer, and Figure 10 is a graph showing the maximum inter-layer deformation angle of each layer.

[0084] As shown in Figure 8, the deformation of the seismic isolation layer (displacement of one layer) is approximately the same for the seismically isolated building 12 of this embodiment and the seismically isolated building 900 of the comparative example. However, as shown in Figure 9, the acceleration response of the seismically isolated building 12 of this embodiment is smaller than that of the seismically isolated building 900 of the comparative example, and the reduction effect on the acceleration response of the first building section 100 is particularly large. Furthermore, as shown in Figure 10, the inter-story drift angle is also smaller for the seismically isolated building 12 of this embodiment than for the seismically isolated building 900 of the comparative example, showing a reduction effect.

[0085] Thus, when the deformation of the seismic isolation layer is kept to the same extent, the acceleration response of the seismically isolated building 12 in this embodiment is reduced compared to the seismically isolated building 900 in the comparative example, resulting in a reduction in both acceleration response and inter-story drift angle.

[0086] <Other> Furthermore, the present invention can be implemented in various forms without departing from the spirit of the invention.

[0087] For example, in the above embodiment, the upper end of the second building section 200 was rigidly connected to the sixth layer 26 directly above the position K which is a secondary mode node in the first building section 100, but it is not limited to this. The upper end of the second building section 200 may be rigidly connected to any layer above the position K which is a secondary mode node in the first building section 100, and may be rigidly connected to the seventh layer 27, the eighth layer 28, and the ninth layer 29.

[0088] Furthermore, if the position K that constitutes a secondary mode node in the first building section 100 coincides with a layer, the upper end of the second building section 200 is rigidly connected to the layer above the layer where the coincidence occurs.

[0089] Furthermore, in the above embodiment, for example, both the horizontal stiffness of the second building section 200 and the damping performance of the second damping device 220 were adjusted so that the amount of horizontal deformation of the second seismic isolation layer 32 in the secondary mode was 0 or approximately 0, but the invention is not limited to this. Either the horizontal stiffness of the second building section 200 or the damping performance of the second damping device 220 may be adjusted so that the amount of horizontal deformation of the second seismic isolation layer 32 in the secondary mode is 0 or approximately 0.

[0090] Here, Figure 11 is a graph showing the case where the reinforcement ratio α of the second building section 200 is 1.0, and the damping performance of the second damping device 220 is adjusted so that the horizontal deformation of the second seismic isolation layer 32 is 0 or approximately 0. In other words, the horizontal stiffness of the second building section 200 is 1 / 3 that of the lower building section 904 of the building section 902 of the comparative example seismic isolation building 900, and the damping performance of the second damping device 220 is adjusted so that the horizontal deformation of the second seismic isolation layer 32 is 0 or approximately 0. Thus, it is possible to adjust the horizontal deformation of the second seismic isolation layer 32 to be 0 or approximately 0 without reinforcing and adjusting the horizontal stiffness of the second building section 200.

[0091] Furthermore, for example, the seismic isolation building 12 in the above embodiment has a center core structure, and a part of the center core is designated as the second building section 200, but it is not limited to this.

[0092] For example, as shown in Figure 12, another example of a base-isolated building 800, a side core structure may be used, with a portion of the side core designated as the second building section 820. Specifically, the base-isolated building 800 has a configuration in which the second building section 820 is provided at intervals on both sides of the lower building section 814, which extends downward from the midpoint in the left-right direction of the upper building section 812 of the first building section 810. The upper end of the second building section 820 is rigidly connected to a layer above the position that corresponds to the node of the second mode of the natural vibration mode in the first building section 810.

[0093] Furthermore, as in the other example of a base-isolated building 700 shown in Figure 13, a second base-isolated building section 720 may be constructed next to a first base-isolated building section 710, and the upper end of the second building section 720 may be rigidly connected to a layer above the position that corresponds to the node of the second mode of the natural vibration mode in the first building section 710.

[0094] Furthermore, for example, in the actual embodiment described above, the upper end of the second building section was rigidly connected to a layer above the position that constitutes a node of the second-order mode of the natural vibration modes in the first building section, but the structure is not limited to this. The upper end of the second building section may also be rigidly connected to a layer above the position that constitutes a node of the third-order mode or higher of the natural vibration modes in the first building section.

[0095] Furthermore, for example, in the above embodiment, the base-isolated building was a base-isolated structure, but it is not limited to this, and an intermediate base-isolated structure may also be used.

[0096] Furthermore, multiple embodiments and variations can be combined and implemented as appropriate. [Explanation of Symbols]

[0097] 10. Building structure 12. Seismic isolation buildings 20. Building section (an example of a superstructure) 30 Seismic isolation layer 31 First seismic isolation layer 32 Second seismic isolation layer 50 Foundation (an example of a substructure) 100 First Building Department 110 First seismic isolation bearing 120 First damping device 200 Second Building Section 210 Second seismic isolation bearing 220 Second damping device 700 Seismic isolation buildings 710 First Building Department 720 Second Building Section 800 Seismic isolation buildings 810 First Building Department 820 Second Building Section K-order mode node position (an example of higher-order mode node position)

Claims

1. The first building section of the seismic isolation structure is constructed on top of the first seismic isolation layer, which is composed of a first seismic isolation bearing and a first damping device installed in the lower structure, The second building section of the seismic isolation structure is constructed at a distance from the first building section on top of the second seismic isolation layer, which is configured by installing a second seismic isolation bearing and a second damping device on the aforementioned substructure, Equipped with, The aforementioned first seismic isolation bearing has a restoring force, The second seismic isolation bearing is assumed to have a restoring force of approximately 0. The second building section is rigidly connected to a layer above the position where the upper end of the first building section is a node of a higher-order mode of the natural vibration mode. The damping performance of the second damping device is adjusted so that the amount of horizontal deformation of the second seismic isolation layer in the higher-order mode is 0 or approximately 0. Building structure.

2. In addition to the damping performance of the second damping device, the horizontal rigidity of the second building section is adjusted so that the amount of horizontal deformation of the second seismic isolation layer in the higher-order mode is 0 or approximately 0. The building structure according to claim 1.

3. The damping performance of the second damping device is higher than that of the first damping device. The building structure according to claim 2.

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